1. Field of the Invention
The present invention relates to an NC (numerically controlled) machine tool which comprises a plurality of axes for movement for moving a movable unit, and display means for displaying positional coordinates of the movable unit with respect to the plurality of axes.
2. Description of the Prior Art
One exemplary NC machine tool of the aforesaid type is shown in FIG. 6, which is a block diagram schematically illustrating the construction of the NC machine tool.
As shown, the NC machine tool 50 includes a machine tool 10, an NC (numerical controller) 30 and a PLC (programmable controller) 40 for controlling operating portions of the machine tool 10, and an operation panel 20 for operating the respective operating portions of the machine tool 10 via the NC 30 and the PLC 40. In general, the NC 30 and the PLC 40 constitute a numerical control apparatus.
The machine tool 10 includes a movable unit 11 such as a carriage, and a plurality of drive mechanisms 12 each adapted to move the movable unit 11 along an axis for movement. In general, there are provided a plurality of axes for movement, for example, X-axis, Z-axis and C-axis, and the drive mechanisms 12 are respectively provided in association with the axes so that the movable unit 11 can bemoved along the respective axes.
More specifically, the drive mechanisms 12 each include a servo motor 13 for driving the movable unit 11, a servo amplifier 14 for controlling the operation of the servo motor 13, and an position detector (encoder) 16 for sensing an angular position of the servo motor 13. The drive mechanism 12 and a controller 31 to be described later constitute a so-called semi-closed loop servo mechanism, so that a position detection signal detected by the position detector 16 is fed back to the controller 31.
The operation panel 20 includes: a mode selection switch 21 which permits an operator to select a desired control mode of the drive mechanisms 12; an axis selection switch 22 which permits the operator to select one of the plurality of axes along which the movable unit 11 is to be moved by manual operation; a pulse handle 23 to be manually operated to move the movable unit 11; a multiplication factor selection switch 24 which permits the operator to select a desired one of predetermined multiplication factors of a movement amount of the movable unit 11 for each pulse outputted from the pulse handle 23; and a CRT display (hereinafter referred to simply as xe2x80x9cCRTxe2x80x9d) 25 for displaying positional coordinates of the movable unit 11 and the like.
The mode selection switch 21 includes a plurality of key switches for automatic operation modes such as a memory operation mode and a programmable tape operation mode and manual operation modes such as a jogging mode and a handle feed mode. When one of the key switches for a desired mode is pressed, a selection signal is inputted from the key switch to the PLC 40 to allow for an operation in the desired mode. Where the movable unit 11 is to be operated with the use of the pulse handle 23, the handle feed mode is selected.
The axis selection switch 22 includes a plurality of key switches for the respective axes, e.g., X-axis, Z-axis and C-axis. When the handle feed mode is selected by the mode selection switch 21, a desired one of the axes is selected by pressing the corresponding key switch of the axis selection switch 22, whereby a selection signal is outputted from the key switch to the PLC 40. This permits the movable unit 11 to be moved along the selected axis.
When the pulse handle 23 is rotated, a pulse signal is generated in accordance with the amount of the rotation thereof. More specifically, the pulse handle 23 is manually rotated, whereby a pulse signal of a predetermined pulse number is generated in accordance with an angular movement amount of the pulse handle 23 and then inputted to the NC 30.
The multiplication factor selection switch 24 includes a plurality of key switches, for example, for multiplication factors of xc3x971, xc3x9710 and xc3x97100. When one of the key switches for a desired multiplication factor is pressed, a selection signal is inputted from the key switch to the PLC 40.
The PLC 40 controls: fundamental functional operations for the machine tool such as various interlock operations and operations of a spindle, a magazine, an automatic tool changer (ATC), an automatic pallet changer (APC) and a tool post; and auxiliary functional operations for the machine tool such as operations of jigs to be incorporated in the machine tool in accordance with a workpiece and a working process, a cutting oil feeder, a chip remover and a workpiece loader/unloader. The PLC 40 receives the signals from the mode selection switch 21, the axis selection switch 22 and the multiplication factor selection switch 24. Where the selection signal inputted from the mode selection switch 21 indicates the selection of the handle feed mode, the PLC 40 outputs the axis selection signal and the multiplication factor selection signal from the axis selection switch 22 and the multiplication factor selection switch 24, respectively, to the NC 30.
The NC 30 numerically controls the respective drive mechanisms 12 on the basis of a machining program, MDI data, a manual rapid feeding signal, a manual operation pulse signal and the like. The NC 30 comprises: the aforesaid controllers 31 respectively associated with the drive mechanisms 12; distribution means 32 which generates a pulse signal (movement command signal) by multiplying the pulse number of the pulse signal directly inputted from the pulse handle 23 by the selected multiplication factor specified by the multiplication factor selection signal inputted from the multiplication factor selection switch 24 via the PLC 40, and outputs the generated pulse signal to one of the controllers 31 specified by the selection signal inputted from the axis selection switch 22 via the PLC 40 and to positional coordinate calculating means 34 to be described later; the positional coordinate calculating means 34 for calculating positional coordinates of the movable unit 11 in a machine coordinate system and/or a work coordinate system on the basis of the pulse signal (movement command signal) inputted from the distribution means 32; and display control means 33 for outputting the calculated positional coordinate data together with display format data to the CRT 25 and displaying the positional coordinate data on the CRT 25.
When the movable unit 11 is to be moved by manual operation with the use of the pulse handle 23 in the NC machine tool 50 of the aforesaid construction, the handle feed mode is selected by pressing the corresponding key switch of the mode selection switch 21, and one of the axes and one of the multiplication factors which are to be employed for the movement of the movable unit 11 are respectively selected by pressing the corresponding key switches of the axis selection switch 22 and the multiplication factor selection switch 24. Thus, signals are respectively inputted from the mode selection switch 21, the axis selection switch 22 and the multiplication factor selection switch 24 to the PLC 40, and an axis selection signal and a multiplication factor selection signal are inputted from the PLC 40 to the distribution means 32 of the NC 30.
When the pulse handle 23 is rotated, a pulse signal is generated by the pulse handle 23 in accordance with the angular movement amount thereof, and inputted to the distribution means 32. By multiplying the pulse number of the inputted pulse signal by the selected multiplication factor, a pulse signal (movement command signal) is generated, which is in turn inputted from the distribution means 32 to one of the controllers 31 specified by the axis selection signal. Thus, the corresponding drive mechanism 12 is controlled by the controller 31 to move the movable unit 11 by a distance according to the inputted pulse signal.
The pulse signal (movement command signal) from the distribution means 32 is also inputted to the positional coordinate calculating means 34. On the basis of the pulse signal (movement command signal), the positional coordinate calculating means 34 calculates positional coordinates of a target location to which the movable unit 11 is to be moved. The positional coordinate data are outputted to the display control means 33, which in turn displays the positional coordinate data in a predetermined format on the CRT 25.
One exemplary display image thus displayed on the CRT 25 is shown in FIG. 7. As shown, positional coordinates of the movable unit 11 are listed along with the designations of the axes.
With the NC machine tool 50, an operator can move the movable unit 11 to the exact target location by operating the pulse handle 23 while viewing the display image on the CRT 25 to accurately keep up with the current position of the movable unit 11.
However, the aforesaid conventional NC machine tool 50 suffers from the following drawbacks.
When the movable unit 11 is moved by the manual operation, the operator performs the moving operation while visually checking the actual position of the movable unit 11. Therefore, the operator often takes his eyes off the CRT 25. In the conventional case where the positional coordinates of the movable unit 11 are listed for the respective axes on the CRT 25, however, it is difficult for the operator to instantaneously pick up data concerning the axis of interest from the listed positional coordinate data when he views the display image on the CRT 25 to check the current position of the movable unit 11. This makes a series of moving operations troublesome, prolonging the time required for the moving operations.
For improvement of the efficiency of the moving operation of the movable unit 11, an operator familiar with the operation of the operation panel 20 sometimes blindly operates the axis selection switch 22 and the pulse handle 23 while mainly checking the movable unit 11 and the CRT 25. In this case, however, the operator often erroneously operates the axis selection switch 22 to select an unintended axis, whereby the movable unit 11 is inadvertently moved along the unintended axis. This results in a reduction in the efficiency of the moving operation.
In view of the foregoing, it is an object of the present invention to provide an NC machine tool which allows for easy check of positional coordinate data of a movable unit on a selected axis on a display in a manual operation mode.
In accordance with the present invention, there is provided an NC machine tool which comprises: at least one movable unit; drive means having a plurality of axes for movement and operative to move the movable unit along the axes; manual operation means for driving the drive means by manual operation; axis selection means for selecting one of the plurality of axes along which the movable unit is to be moved by the manual operation means; positional coordinate calculating means for calculating positional coordinates of the movable unit with respect to the plurality of axes on the basis of a movement command; display means capable of displaying the positional coordinates of the movable unit with respect to the plurality of axes at least in a list form; and display control means for controlling the display means to display the positional coordinates at least in the list form on the display means, wherein the display control means receives a selection signal indicative of the selected axis from the axis selection means in a manual operation mode, and controls the display means to display a positional coordinate of the movable unit with respect to the selected axis in a display form different from a display form of the positional coordinates of the movable unit with respect to the other axes on the display means, whereby the positional coordinate of the movable unit with respect to the selected axis is distinguishable from the positional coordinates with respect to the other axes on the display means.
With this arrangement, the positional coordinates of the movable unit with respect to the plurality of axes are calculated on the basis of the movement command, and the calculated positional coordinates are displayed in the list form on the display means. When the movable unit is moved by the manual operation, the coordinate of the movable unit with respect to the axis selected by the axis selection means is displayed on the display means in the display form different from the display form of the positional coordinates of the movable unit with respect to the other axes.
Thus, the operator can easily recognize the coordinate of the movable unit with respect to the selected axis in distinction from the positional coordinates of the movable unit with respect to the other axes to smoothly and readily perform the moving operation. Even if the operator inadvertently selects an unintended axis, he can instantaneously recognize the selection of the unintended axis, thereby preventing such an inconvenience that the movable unit is moved along the unintended axis. Thus, the reduction in the efficiency of the moving operation can be prevented which may otherwise occur due to selection of the unintended axis.
The display control means may be adapted to control the display means to display a list of the positional coordinates of the movable unit with respect to the plurality of axes and, at the same time, display the positional coordinate of the movable unit with respect to the selected axis separately from the list of the positional coordinates on the display means in the manual operation mode. With this arrangement, the positional coordinate of the movable unit with respect to the axis selected by the axis selection means is displayed on the display means separately from the positional coordinates of the movable unit with respect to the other axes. Therefore, the operator can easily recognize the positional coordinate of the movable unit with respect to the selected axis in distinction from the positional coordinates of the movable unit with respect to the other axes.
The display control means may be adapted to control the display means to display the positional coordinate with respect to the selected axis on a greater scale separately from the list of the positional coordinates with respect to the plurality of axes on the display means in the manual operation mode. With this arrangement, the positional coordinate with respect to the axis selected by the axis selection means is displayed on a greater scale on the display means separately from the positional coordinates with respect to the other axes. Therefore, the operator can more easily recognize the coordinate of the movable unit with respect to the selected axis in distinction from the positional coordinates with respect to the other axes.
The display control means may be adapted to control the display means to display a list of the positional coordinates with respect to the plurality of axes on the display means and, in the manual operation mode, display only the positional coordinate with respect to the selected axis on the display means instead of the list of the positional coordinates with respect to the plurality of axes in response to the reception of the selection signal from the axis selection means. With this arrangement, only the positional coordinate with respect to the axis selected by the axis selection means is displayed on the display means, so that the operator can further more easily and accurately recognize the positional coordinate with respect to the selected axis. Thus, the moving operation can be performed more efficiently.
The manual operation means includes multiplication factor selection means for selectively changing a multiplication factor which defines the ratio of a movement amount of the movable unit to a manual operation amount, and the display control means is adapted to receive a selection signal indicative of the selected multiplication factor from the multiplication factor selection means and control the display means to display the positional coordinates of the movable unit together with the selected multiplication factor on the display means. With this arrangement, the selected multiplication factor is displayed together with the positional coordinate with respect to the selected axis on the display means, so that the operator can easily and accurately estimate the movement amount of the movable unit to be moved by the manual operation. Thus, the operator can properly and accurately perform the manual operation.